> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Alan B. Pearce
> Sent: Friday, February 10, 2006 8:39 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC]: Getting started with USB
> 
> 
> >The FDTI chip normaly emulates a comport,
> 
> While I agree this is true for the FT232 serial chips, I am 
> not sure about the FT245. I was assuming it looked like a 
> parallel printer port to the OS.

No.  There are two drivers available from FTDI, the VCP (Virtual Comm
Port) and D2XX native mode drivers.

All FTDI chips when used with the VCP drivers look like a serial port to
the PC.  It is also possible to make the device look like a serial port
using the D2XX drivers too but not nearly as simple.

Depending on the chip, the other side will be the usual serial port
lines including control lines or an 8-bit parallel port with 4 FIFO
(different depths, depending on exact chip chosen) handshaking lines.
In the case of the 8-bit parallel port I/O, data is de-serialized and
presented on the 8 I/O lines.  There is also a "bit-bang" mode available
on all chips that allows the PC to toggle lines remotely.

The maximum claimed throughput for the VCP drivers is 300kbyte/sec, for
the D2XX drivers it is 1Mbyte/sec.  In practice I have never been able
to SUSTAIN 1Mbyte/sec with the chip, something always gets bound up.
For a sustained transfer (ie hours at a time) I've gotten 880kbyte/sec.
I have seen it burst out at 1Mbyte/sec.  Some dependence on the PC and
quality of the application software.

Rob
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